Make sure the build of jbuilder doesn't call ocamlfind or opam

src/context.ml

@@ -160,7 +160,7 @@ let extend_env ~vars ~env =
       imported
     |> Array.of_list
 
-let create ~(kind : Kind.t) ~path ~base_env ~env_extra ~name ~merlin =
+let create ~(kind : Kind.t) ~path ~base_env ~env_extra ~name ~merlin ~use_findlib =
   let env = extend_env ~env:base_env ~vars:env_extra in
   let opam_var_cache = Hashtbl.create 128 in
   (match kind with
@@ -193,22 +193,25 @@ let create ~(kind : Kind.t) ~path ~base_env ~env_extra ~name ~merlin =
   in
   let ocamlc_config_cmd = sprintf "%s -config" (Path.to_string ocamlc) in
   let findlib_path =
-    (* If ocamlfind is present, it has precedence over everything else. *)
-    match which "ocamlfind" with
-    | Some fn ->
-      (Future.run_capture_lines ~env Strict
-         (Path.to_string fn) ["printconf"; "path"]
-       >>| List.map ~f:Path.absolute)
-    | None ->
-      (* If there no ocamlfind in the PATH, check if we have opam and assume a standard
-         opam setup *)
-      opam_config_var ~env ~cache:opam_var_cache "lib"
-      >>| function
-      | Some s -> [Path.absolute s]
+    if use_findlib then
+      (* If ocamlfind is present, it has precedence over everything else. *)
+      match which "ocamlfind" with
+      | Some fn ->
+        (Future.run_capture_lines ~env Strict
+           (Path.to_string fn) ["printconf"; "path"]
+         >>| List.map ~f:Path.absolute)
       | None ->
-        (* If neither opam neither ocamlfind are present, assume that libraries are in
-           [dir ^ "/../lib"] *)
-        [Path.relative (Path.parent dir) "lib"]
+        (* If there no ocamlfind in the PATH, check if we have opam and assume a standard
+           opam setup *)
+        opam_config_var ~env ~cache:opam_var_cache "lib"
+        >>| function
+        | Some s -> [Path.absolute s]
+        | None ->
+          (* If neither opam neither ocamlfind are present, assume that libraries are in
+             [dir ^ "/../lib"] *)
+          [Path.relative (Path.parent dir) "lib"]
+    else
+      return []
   in
   both
     findlib_path
@@ -317,7 +320,7 @@ let initial_env = lazy (
   Lazy.force Ansi_color.setup_env_for_ocaml_colors;
   Unix.environment ())
 
-let default ?(merlin=true) () =
+let default ?(merlin=true) ?(use_findlib=true) () =
   let env = Lazy.force initial_env in
   let rec find_path i =
     if i = Array.length env then
@@ -330,7 +333,7 @@ let default ?(merlin=true) () =
   in
   let path = find_path 0 in
   create ~kind:Default ~path ~base_env:env ~env_extra:String_map.empty
-    ~name:"default" ~merlin
+    ~name:"default" ~merlin ~use_findlib
 
 let create_for_opam ?root ~switch ~name ?(merlin=false) () =
   match Bin.opam with
@@ -355,7 +358,7 @@ let create_for_opam ?root ~switch ~name ?(merlin=false) () =
     in
     let env = Lazy.force initial_env in
     create ~kind:(Opam { root; switch }) ~path ~base_env:env ~env_extra:vars
-      ~name ~merlin
+      ~name ~merlin ~use_findlib:true
 
 let which t s = which ~cache:t.which_cache ~path:t.path s
 

src/context.mli

@@ -126,7 +126,10 @@ val create_for_opam
   -> unit
   -> t Future.t
 
-val default : ?merlin:bool -> unit -> t Future.t
+(** If [use_findlib] is [false], don't try to guess the library search path with opam or
+    ocamlfind. This is only for building jbuilder itself, so that its build is completely
+    independent of the user setup. *)
+val default : ?merlin:bool -> ?use_findlib:bool -> unit -> t Future.t
 
 val which : t -> string -> Path.t option
 

src/main.ml

@@ -15,6 +15,7 @@ let package_install_file { packages; _ } pkg =
 
 let setup ?(log=Log.no_log) ?filter_out_optional_stanzas_with_missing_deps
       ?workspace ?(workspace_file="jbuild-workspace")
+      ?(use_findlib=true)
       ?only_packages () =
   let conf = Jbuild_load.load () in
   Option.iter only_packages ~f:(fun set ->
@@ -35,7 +36,8 @@ let setup ?(log=Log.no_log) ?filter_out_optional_stanzas_with_missing_deps
   Future.all
     (List.map workspace.contexts ~f:(function
      | Workspace.Context.Default ->
-       Context.default ~merlin:(workspace.merlin_context = Some "default") ()
+       Context.default ~merlin:(workspace.merlin_context = Some "default")
+         ~use_findlib ()
      | Opam { name; switch; root; merlin } ->
        Context.create_for_opam ~name ~switch ?root ~merlin ()))
   >>= fun contexts ->
@@ -143,7 +145,8 @@ let bootstrap () =
       anon "Usage: boot.exe [-j JOBS] [--dev]\nOptions are:";
     let log = Log.create () in
     Future.Scheduler.go ~log
-      (setup ~log ~workspace:{ merlin_context = Some "default"; contexts = [Default] } ()
+      (setup ~log ~workspace:{ merlin_context = Some "default"; contexts = [Default] }
+         ~use_findlib:false ()
        >>= fun { build_system = bs; _ } ->
        Build_system.do_build_exn bs [Path.(relative root) (pkg ^ ".install")])
   in
@@ -152,3 +155,5 @@ let bootstrap () =
   with exn ->
     Format.eprintf "%a@?" (report_error ?map_fname:None) exn;
     exit 1
+
+let setup = setup ~use_findlib:true